That is definitely not intentional. Is the music cutting out completely, or is it just dipping down in volume?

One suggestion that might work is to change the audio settings. On Steam, you can access the setup options by following these steps:

- right click on the game in your library- select properties- press "set launch options"- type "--setup" and press OK

The next time you run the game, the setup options will pop up on your screen. At the bottom you will see the sound options. Try changing the "digital sound" dropdown menu to something else and see if it works.